The reduced pressure frozen mold casting process has been known as a recycling-based casting method with several advantages, such as improvement of the work environment, reduction of industrial waste and significant improvement of product yield. In this method, only water and silica sand were used to make mold, which was rapidly frozen at −40°C, then molten metal was poured into it. In the present investigation, samples were made by the reduced pressure frozen mold casting process and previous processes, and comparisons of their mechanical properties, especially the fatigue strength, were reported.As a result, it was clarified that cast iron made by the reduced pressure frozen mold casting process has a sufficient strength; therefore the reduced pressure frozen mold casting process was expected to be applicable to other castings that have made by previous casting processes.